Centrifugal pump



C. V. KERR.

CENTRIFUGAL PUMP.

APPLICATION FILED OCT. 29. 1917.

1 334,46 1 q 7 Patented Mar. 23, 1920 3 SHEETS SHEET I.

C. V. KERR.

CENTRIFUGAL PUMP.

APPLICATION FILED ucr. 29, 1917.

Patented Mar. 23, 1920.

3 $HEETS-SHEET 2.

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1 for "a v C. V. KERR. CENTRIFUGAL PUMP. APPLICATION mEo'ocnzs. 1917.

1,334,461. Patented Mar. 23,1920.

3 SHEETS-SHEET 3- :10 GENERAT NG LINE J5 INLET soar:

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- mu) STATES PATENT 0 lllllltl tLES V. KERR, OF'A URORA, ILLINOIS,ASSIGNOR TO THE AMERICAN WELL WORKS,

OF AURORA, ILLINOIS, A COBPORA'IZIQN OF ILLINOIS.

vcnu'rruriuear. PUMP.

inseam.

Specification of Letters Patent.

Patented Mar. $3, 192d.

lpplication'filed October 29,1917. Serial No. recent.

' lllinois, have invented certain new and usefor the accomplishment ofthe purposes hereinafter set forth.

Pumps having impellers of the propeller or screw type are commonly desgned to raise large volumes of water to a small height at a slow speedof rotation and it has been found that their efiiciency is new ally low.

The object of this invention is to modify he present type of such pumpsso as to obtain a greater range of pumping head, in creased rotativespeed. for direct drive by steam turbines or other high speed motors, ahigher efficiency and improved and simplihed construction.

it further object of my invention is to construct and arrange the bladeson the impeller which lifts and propels the fluid so that the same, inview of its' hi h velocity,

will act gradually in changing t 0 directionof the movement of the fluidthereby avoidingchurning of the same ,which by absorbing power reducesthe efiici ency of the pump. The working surface of the blade in theordinary screw impeller of centrifugal pumps' is generated by a linewhich reniains perpendicular to the shaft or axis "While moving axiallalong a curved directrier. Such an impel er can give an impulse to thefluid pumped only at pick-up by the inlet edge of the blade, and resultsin waste of energy by striking the fluid-at a large angle, and if thepump is run at high velocity to obtain greater pressures, causes greatloss of efficiency and noisy action. In the impeller of my constructionthe entrance angle of the blades is very small and enables the fluidtobe picked up close to the shaft, gradually increasing its velocity as itis carried toward the peripheryofthe impeller and to the outlet. Saidimpeller is also arranged and constructed with respect to the annularoutlet so that it will automatically act under all conditions ofservice, to uniformly balance the pressure on both sides or fluidreceiving surfaces of the impeller, and at the same time centralize saidimpeller with respect to the annular or nozzle outlet for the fluid tothe discharge opening. a

To secure to the fullestextent the various objects above set forth Ihave devised the present improvements, a preferred form of which isshown inthe accompanying three sheets forming part of thisspecification, in

. which similar reference characters indicate the same parts throughoutthe several figures of the drawings.

The invention consists of structural char acteristics and relativearrangements of ele ments, which will be hereinafter more fully andclearly described, and particularly pointed out in the appended claims.

In the drawings I Figure 1 is a transverse section 'of the pump on theline 1-1 of Fig. 2;

Fig. 2 is a section on line Ill-11 of Fig. 1; Fig. 3 is a transversesection of the left hand head of the casing on the line lII-IIl of Fig.4:;

Fig. 4 is an end view of the left hand head of the casing shown insection in Fig. 3;

Fig. 5 is a transverse section of the left hand Wearing or balance ringon the line V-V of Fig. 6;

Fig. 6 is anend view of the wearing or balance ring shown in section inFig. 5;

.Fig. 7 is a detail and enlarged peripheral view of the runner orimpeller, one half being in elevation and the other half in section,showing also a part of the balance ring inlpection in its relativeposition to the im- P Fig. 8 is an end view of one half of the impeller,forming the inner central part of the impeller. 3

Fig. 9, represents the development of the helical directrix of variablepitch, and

10, represents the development of the casing having a base or stand 10,a Water inlet 11 preferably branched or divided into two symmetricalvolute suction chambers.

12, 12, an interior or central discharge chamber 13 preferably of voluteform and ending in the discharge nozzle 14.

15, 15, are bearing heads suitably bolted or fastened tothe casing,closing the suction chambers 12, 12, and projecting into them. Thesebearing heads have central able bearings 21, 21 for the shaft of theimpeller. These bearings may be of any suitable character, butpreferably of the dust-proof type with lubricating rings as shown.

The casing may be made in more than one part, but as shown in thedrawing can easily and preferably be manufactured in one piece as alljoints and packings that may cause leakage are thereby avoided.

The propeller or screw impeller 22, is preferably made in two sections,but may be made solid or in one piece if desired,

It is secured in its place on the shaft by a key and by means of twosleeves- 24, 24 which are firmly fastened to the shaft by the right andleft hand screw'threads 25, 25 on the shaft 23 or by other suitablemeans. These sleeves are so arranged that they rigidly hold together thetwo sections of the impeller in a fixed relation and keep them fromslipping longitudinally on the shaft. The impeller with the sleeves andthe shaft are held in proper central position in the casing by means ofthe two set collars 26, 26 which abut against the inner faces of thebearings 21, 21. v

To each of the bearing heads 15, 15, there is attached a wing 27, shownin detail in Figs. 2, 3 and 4 extending permanently acrossthe'be'aringvhead' close to theshaft, in order to sto the whirling ofthe fluid around the sha t and made of such form as not to impede thespiral forward flow into balancing rings 29, 29 eafch of which co'nsistsof'a plate 30, with a central circular opening 30' admitting the fluidfrom the suction chamber to the central parts of the impeller and aninner ring 31, fitting tightly into the casing, and of such innerdimenslon's of the ring and the plate that the impeller may freelyrotate therein. These wearing or balancing rings 29, 29 form anautomatic and perfect method of balancing the impeller 22, andpermitting it and the shaft 23, to move freely in a central positionwithout touching the wearing surfaces 29, 29, thus securing a hydraulicbearing with a very slight leakage of fluid and with a minimum offriction. lVhen the pump is in operation the fluid is drawn from thesuction chambers 12, 12 through the impeller ,into the discharge chamber13. The pressure in chamber 13 forces a small amount of liquid throughthe narrow spaces between the sta tionary plate 30 and the inner rin 31of the wearing ring 29, and the rotating adjoining surfaces or shroudring of the impeller 22, causing a slight leakage.

The collars 26, 26 on the shaft 23 are set to permit the surfaces of theimpeller to come'incontact with the opposing surfaces of the wearingrings 29, 29 and then any unbalanced axial pressure on the impeller willmove the latter and the shaft 23. Assuming this movement to be towardthe right in Fig. 1, then the surface of the impeller 22 on the rightwill contact with the opposing surface on the wearing ring 29, and closethe passage along the interior of the latter. At the same time thepassage between the impeller 22 and the wearing ring 29, on the leftside is enlarged and a larger flow of fluid permitted, this resulting ina reduction of the pressure on the left side and an increase of thepressure on the right side,

- thereby equalizing the end pressure on the impeller. If the excess'ofpressure is toward the left the operations will be reversed.

The wearing rings 29 are held in their position by being closely fittedinto place and by two or more screws 32, see Fig. 7.

Referring to Figs. 7 and 8, it will be seen that the impeller 22consists of two parts, each of which is an integral structure and whenassembled they form an impeller having two separate suctions or intakes33, 33 and two separate outlet openings 34, 34, the latter conveying anddischarging the fluid into the central chamber 13. The two parts of theimpeller 22 are held together in proper relation and secured on theshaft 23, by the sleeves 24, 24 engaging threaded sections 25, 25 on theshaft, and prevented from rotating by the keys 35, 35. I have shown theimpeller 22 preferably made in two parts because of the greater ease ofmanufacture in that form, but it may be made in one part with veryslight changes.

The im eller when assembled forms a pcriphery of V-shaped or oonoid'alsections 36, 36 having an angle a with the axis of the impeller. Thevanes or blades are so placed on the conoidal sections 36, 36 that theyform proper working surfaces and they and the conoidal sections areincased by the shroudlll , preferably uniformly increasing as the bladeing 37 which is so fitted at its periphery 38 to the inner ring of thebalance or wearing ring 29 at 39, that the impeller 22 will run freely,but as close as practicable within the the wearing ring 29, however,leaving a very small space or opening that the fluid may reach the spacebetween the end surfaces 40 of the impeller and the plate of the wearingor balance ring 29 at 41, for the purpose of automatically balancing theimpeller 22 by hydraulic pressure on its opposite ends andk eeping it ina central position within the casing as previously described.

The blades 42 of the impeller may be of any suitable number and are ofhelical or screw form, and their surfaces are generated by a linefollowing a helical .directrix of constant pitch, having a very smallangle of entrance at the inlet edge of the blade with the plane ofrotation, gradually and surface approaches the periphery of the impellerat the discharge edge. Thus referring to .Fig. -7 it will be seen thatat A, A, or the inlet edge, the line generating the blade surfaces ofthe impeller 22, makes an angle of 15 with the plane of rotation; at B,B, an angle of 30; at C, C, an angle of 45; at D, D, 60; and at E, E, ordischarge edge it is 75. The purpose of this construction is to pick upthe fluid at the inlet edge with a small angle of impulse and thenincrease the acceleration by the greater angles of the generating line,until the action approximates that of the purely centrifugal blade atits discharge. The generating line may be gin at the inlet edge with azero angle and increase to 90 at the discharge edge, or the rate ofinclination of the generating line may be varied, as it moves along thehelical directrix and the shaft, or the pitch of the helical directrixmay be variable as shown in Fig. 9 instead of uniform, as shown in Figs,7 and 10, or any other of the well known variations of the screwpropeller may be used as suits the conditions under which the pump is torun, as regards speed of rotation, pressure and quantity of discharge.

Assuming the parts of the pump are assembled and adjusted as shown inFig. 1, and the pump primed or completely filled with liquid beforestarting, as the impeller 22 is rapidly rotated, it picks up the liquidto be pumped at its inlet edges or intakes 33, 33, after passing fromthe inletll into the V0- lute suction chambers 12,12, at a small angleof impulse, and gradually accelerates said liquid during its passageoverthe surfaces of the blades 42, and throws it at the velocity requiredfrom the discharge edges or outlets- 34, .34 through the annular nozzleinto the volute discharge chamber 13 in a manner approximating that of acentrifugal blade at its discharge, from whence it is finally dischargedthrough the nozzle 14.

" inlet 11 and inlets of the impeller 22, entirely stop the liquidwithin the suction chambers 12, 12 from whirling around the shaft 23,and without sacrificing the advantage due to spiral forward flow oftheliquid in the suction chambers 12, 12 into the intakes 33, 33 of theimpeller 22, thereby enabling the impeller to readily take up andconserve the velocity which the liquid has gained in passing through theinlet 11 and suction chambers 12, 12. a It will also be seen that fromthe construction and arrangement of the various elements of the pump theinlet edges of the impeller, blades may be sharp compared with the usualcentrifugal blades and machined in the plane of rotation, therebyenabling said edge to be easily made true and sharpand capable ofpicking up the liquid close to the shaft at a high rate of speed.

Furthermore, in the design of the pump shown, the contact surfacesbetween the easing 9, bearing heads 15, and wearing or balancing rings29, can be machined smooth and accurately which will permit the easy andfluid tight assembling of these parts Without loss of time in fittingand use of gaskets, and as the impeller is relatively small in diameter,it may be withdrawn with one balance ring 29 through the opening in thecasing 9 for the bearing head 15.

From the foregoing descriptions, it will be seen that this centrifugalpump is of simple construction and minimum cost of manufacture, easilyaccessible in all its parm, provided with all means for taking up wear,can be made of any suitable material as cast iron, steel, bronze,aluminum, etc., is readily adjusted and will run noiselessly and withgreat eliiciency under varying conditions of speed, pressure,"and volumedischarged. It will also be seen that this type of impeller and pump canreadily be designed and constructed for operation in horizontal, angularor vertical positions.

What I claim is:

1. A centrifugal pump comprising a retary shaft, an impeller on saidshaft, said impeller having a plurality of working surfaces each ofwhich surfaces is generated by a line making a variable angle with theaxis of the shaft while moving along said'axis and lided by a helicaldirectr-ix having a sting line being so limited and in such a manner asto form mlet and dlscharge edges on said working surfaces making acuteanvaribd e pitch, the movement of said generdisposed sets ofworkingsurfaces to pick up the liquid in the suction inlet without shockand gradually accelerate and impel the same through the dischargeoutlet, each of said working surfaces being generated by a line making avariable angle with the axis of the shaft while moving along said axisand guided by a helical directrix having a variable pitch, the movementof said generating line being so limited and in such a manner as to forminlet and discharge edges on said working surfaces making acute angleswith the axis of said shaft.

3. A centrifugal pump comprising a casing having a spiral suction inletcommunicating with a discharge chamber, a rotary shaft, an impeller onsaid shaft interposed between the spiral suction inlet and discharchamber, and a spiral wing interpose between the suction inlet andimpeller near the shaft and forming a continuation of the spiral suctioninlet for the purpose of properly guiding the liquid passing through thesuction inlet into the inlet of the impeller and prevent said liquid inthe suction inlet from whirling about the shaft.

4. A centrifugal pump comprising a casing having volute suction inletchambers communicating with and arranged on each side of a dischargechamber, a rotary shaft, an impeller on said shaft interposed betweenthe volute suction inlet and discharge chambers, and a spiral wingarranged Within each of the suction inlet chambers and on each side ofthe impeller near the shaft and forming a continuation of the volutesuction inlet for the purpose of properly guiding the a liquid passingthrough the suction inlet into the-inlet of the impeller and ofpreventing said liquid in the suction inlet from whirling about theshaft. 4

5. A centrifugal pump comprising a casing having a spiral suction inletcommunicating with a discharge chamber, a bearing head secured to thecasing, a rotary shaft supported in said bearing head, an impeller,

on said shaft arranged between the spiral 4 suction inlet and discharge.chamber, and a said suction and discharge chambers, a r0-' tary shaft,an impeller on said shaft-in said lmpeller chamber, a combinedwearingand balancing ring consisting of a plate with,

central opening and an inner ring surrounding said impeller, interposedbetween the impeller and suction chambers and constructed, arranged andcooperating with said impeller to preserve the impeller in positivehydraulic balance by creating a variable pressure chamber between saidimpeller and combined wearing and balancing ring.

"7. A centrifugal pump comprising a casing provided with' suction anddischarge chambers and having an impeller chamber communicating with andarranged between said suction and discharge chambers, a rotary shaft, adouble suction impeller on said shaft in said impeller chamber havinintakes communicating with the suction c 1ambers and outlets with thedischarge chamber, a combined wearing and balancing ring consisting of aplate with central opening and an inner ring surrounding said impeller,interposedbetween the im )eller and the suction chamber on each si e ofthe impeller constructed, arranged and cooperating with said impeller topreserve the same in positive hydraulic balance by creating a variablepressure chamber between said impeller and combined wearing andbalancing rmg.

8. A centrifugal pump comprising a casing rovided with volute-shapedsuction and disc arge chambers and having animpeller chambercommunicating with and arranged between said suction and dischargecham-.

bers', a rotary shaft, an impeller on said shaft in said lmpellerchamber, a'balancing ring interposed between the nnpeller and suctionchamber constructed and arranged to keep the impeller in positivehydraulic balance, and a bearing head on each side of the casing closingthe suction chamber and provided with a wing on its inner side near theshaft of such shape as to form a continuation of the volute of thesuction chamber for the purpose of preventing the liquid in the suctionchambers entering the impeller from whirling around the shaft.

9. In a centrifugal pump, the combination of a casing having suctionchambers and a discharge chamber arranged between said suction chambers,a rotary double suction impeller with blades having helical surfacesinterposed between the suction and discharge chambers, balancingchambeis formed between the outer surfaces of the impeller and acombined wearing and balancing ring consisting of a plate with centralopening and an inner ring surrounding the'impeller and, therebyproviding passages for a' flow of fluid from said discharge to saidsuction chambers, whereby the im eller and the opposing. faces of the beancing ring are adapted to meet and alternately close said passages andautomatically equalize the opposite axial pressures acting on theimpeller.

' 10. .In a centrifugal pump, the combinaclose alternately, wherebyv thepressure in and interposed between said suction cl1am-.

bers and impeller and each ring having a radial and a cylindricalsurface opposing similar surfaces on the periphery of the impeller andcooperating in such a manner as to provide passages through which fluidmay flow from said discharge chamber into the suction chambers, saidpassages constructed, arranged and adapted to meet and the dischargechamber will act and equalize the opposite axial pressures acting on,the

impeller. r

11. In a centrifugal pump, the combination of a casing, havlng suctionand dis- .charge chambers, shaft bearings, a rotary shaft supported insaid bearings, adjustable collars on said shaft adjacent to thebearings, an impeller on the shaft, movable sleeves on the shaft forholding and adjusting the impeller in central position, a combinedwearing and balance ring seated in I the casing on opposite sides of theimpeller and each ring having a radial contact surface adjacent to andoppositely formed to those of the impeller whereby the adjacent inghaving a discharge passage and a suc- I tion passage on each side ofsaid discharge passage, a rotary impeller within said cas- 1n andproviding communication between said suction and discharge passages andhaving portions of its periphery arranged as radial and cylindricalsurfaces, a balance ring attachedto said casing on each side of saidimpeller and having a radial and a cy' lindrical-surface arranged tocooperate with similar surfaces on said impeller to maintain it inpositive hydraulic'balance by creating a variable pressure chamberbetween said impeller and balance ring.

13.-In a centrifiwal pump, the combination of a casing, s aft bearings,a rotary shaft supported in said bearings, adjustable collars on saidshaftand adjacent to said bearings, double suction impelleron the shafthaving portions of its periphery ar rangpd as radial and cylindricalsurfaces,

com in'ed wearing and balancing rings held in said casing on each sideof said impeller, and each having a radial surface for contact with the.1mpeller and a cylindrical surface surrounding said-impeller, and meansfor setting said collars for contact with said bearings at the instantof contact between said radial surfaces on the wearing ring and impellerin case, of axial movement of said shaft for maintaining positivehydraulic and axial balance of said impeller.

In testimony whereof I affix my signature.

CHAR-LES v. KERR.

